Small cell transformation of non‐small cell lung cancer (NSCLC) is commonly recognized as one of the resistance mechanisms to epidermal growth factor receptor (EGFR)‐tyrosine kinase inhibitors (TKIs) in EGFR‐mutant NSCLC treatment, which accounts for 3%–14% of resistant cases.4, 5, 6. The gene discussed is EGFR; the disease is lung cancer.